Emulsifying composition for cosmetic use for producing an o/w pickering emulsion and process for producing this emulsion

ABSTRACT

The application relates to an emulsifying composition, in particular for cosmetic use, allowing an oil-in-water emulsion (O/W) to be obtained, the emulsion comprising at least one cyclodextrin and at least one O/W emulsifier of natural origin with a hydrophilic-lipophilic balance value (HLB) of more than 8. The O/W emulsifier of natural origin can be selected from alkyl polyglucosides, mixtures of at least one alkyl polyglucoside and at least one fatty alcohol, and non-ethoxylated polyol fatty esters. The application also relates to a composition of the Pickering emulsion type, in particular for cosmetic use, containing the emulsifying composition according to the invention, and to the process for preparing such a composition of the O/W Pickering emulsion type, in particular at low temperatures.

The present invention relates to an emulsifying composition of plantorigin which is ready to use and is directly utilizable cold, and whichfinds application especially in the field of cosmetic compositions. Thiscomposition is sufficient by itself and allows the direct stabilizationof an emulsion without the need to add a co-emulsifier of petrochemicalorigin. More particularly, this emulsifying composition enables the easyproduction of very fine O/W emulsions with varied textures, which arehighly compatible with the skin and which, moreover, exhibit a dry andfresh, silky, and nongreasy feel even when the fatty phase content ofthe emulsion is high. This composition also makes it possible toadvantageously reduce the amount of emulsifier of natural originrequired to obtain an O/W emulsion.

An emulsion is a dispersion of a liquid (or of a substance which hasbeen rendered liquid) as fine droplets in another liquid, this liquidbeing immiscible with the first. It exhibits a macroscopicallyhomogeneous appearance, yet appears homogeneous under the microscope.The liquid in droplet form is called the disperse (or discontinuous)phase, whereas the other liquid is called the dispersing (or continuous)phase. In general, an emulsion is composed of water and oil and of twophases (simple emulsion): a hydrophilic (aqueous) phase and a lipophilic(fatty) phase. The emulsions most commonly encountered are emulsionswhich comprise a lipophilic phase dispersed in a continuous aqueousphase, and are referred to as oil-in-water (O/W) emulsions, as opposedto water-in-oil (O/W) emulsions.

Many cosmetic compositions are emulsions, typically simple emulsions,which are stabilized by surfactants, also called emulsifiers. As anexample, document EP 0 685 227 proposes a very complex system ofcosmetic antisun compositions, comprising an aqueous continuous phase, aprotective system capable of screening out UV rays, a surfactant,organic solvents (lower polyols and alcohols), and at least one polymeror, more particularly, a crosslinked copolymer (alkyl acrylates, vinylacetate).

Document FR 2 858 777, in turn, describes an oil-in-water emulsioncontaining at least one fatty substance (fatty acid esters, waxes,butters, natural oils — of plant, animal or marine origin — or syntheticor mineral oils, hydrogenated oils, and mixtures thereof), at least onesurfactant (ethoxylated fatty acid esters of polyglycerol, alcoholethoxylates), at least one co-surfactant, and water.

Document DE 102 39 647 A1, for its part, describes cosmetic and/ordermatological oil/water (O/W) emulsions containing (a) an aqueousphase, (b) an oily phase of 0.5 to 10% by weight of non-polar tomoderately polar oil(s) with a polarity of 20-60 mN/m, (c) 0.005 to 10%by weight of cyclodextrin derivative(s) and optionally other cosmeticand/or dermatological agents, adjuvants and additives.

Document EP 3 037 083 A1, for its part, describes a sun protectioncomposition without emulsifier.

Document FR 2 823 438 A1, for its part, describes an oil-in-wateremulsion, based on a self-emulsifying combination of fatty alcohols andglucolipids in a weight ratio of between 10:1 and 4:1, and it stands outin that it also comprises a viscosifying agent in the fatty phase.

However, the use of surfactants in products intended for application tohumans or animals, whether in topical, oral or another form, may beproblematic. The reason is that the surfactants may damage the cellmembranes. Thus, especially in the cosmetics field, efforts to reducethe potentially harmful effects of surfactants, or even to eliminaterecourse to surfactants, have been authorized.

Thus, one of the aims of the present invention is to provide anemulsifying composition which is able to form a stable emulsion byadding oil or fatty substance when placed in the presence of water, inparticular according to a process referred to as a “cold process”.

Advantageously, this emulsifying composition according to the inventionmakes it possible to significantly reduce the use of surfactants thatare of petrochemical origin and are non-biodegradable, in particularglycol derivatives and ethoxylated or polyethoxylated derivatives.According to another variant, it makes it possible to eliminate the needfor these surfactants of petrochemical origin.

From this standpoint, the composition of the present invention alsoenables the production of Pickering emulsions. Emulsions of this typeare devoid of surfactant and are stabilized by colloidal particles suchas, typically, silicas, which take up position at the interfaces of thecontinuous phase and the disperse phase. In the context of the presentinvention, these colloidal particles are organic particles consisting ofinclusion complexes of at least one cyclodextrin with at least one fattymolecule. These particles have very advantageous compatibility with theskin or the hair, and do not damage animal cell membranes.

This result is all the more noteworthy for the fact that in the priorart, it has been shown that the production of emulsifying systems forcosmetic use, containing cyclodextrins, does not make it possible toobtain emulsions easily and directly under cold conditions: it washitherto necessary to have recourse to conventional surfactants thatwork at high temperature and are generally of petrochemical origin. Thisis the teaching especially of document EP 2 091 502 B1, which describesan O/W emulsion containing water, a fatty substance, a modifiedpolysaccharide, and a cyclodextrin, with the essential feature of thisO/W emulsion being that it contains surfactants with a molecular weightof less than 5000 g/mol in an amount of less than 2% by weight. It wastherefore neither known nor obvious to produce emulsifying systemscontaining cyclodextrins that produce very fine and very stableemulsions without having recourse to ordinary surfactants ofpetrochemical origin.

Another object of the present invention is to provide a composition ofnatural origin. The natural origin of the ingredients used to formulateproducts of everyday use such as cosmetic compositions is nowadays amajor issue, in relation not only to the safeguarding and protection ofour environment but also to the well-being of consumers. In this regard,the composition of the present invention makes it possible to reduce, oreven replace conventional emulsifiers, especially ethoxylatedemulsifiers, which it is nowadays desirable to replace for environmentalissues (poor biodegradability) and safety (ethylene oxide is toxic andflammable).

Another object of the present invention is to provide a ready-to-useemulsifying composition which the formulator can employ very simply,with minimum input of energy, especially by introduction of all of theingredients into a single vessel or reactor (a so-called “one pot”formulation). From the standpoint of its use, the composition to whichthe present invention relates is advantageously utilizable according to“a cold process”, in other words even at ambient temperature, incontrast to many solid or pastelike conventional emulsifiers, such aswaxes, the use of which requires an increase in the temperature (aningredient which needs to be melted and is utilizable “hot”). The notionof cold process includes emulsification processes in which the only heatinput is that due to the energy dissipation caused by mechanicalstirring. By “cold process” is meant that the emulsifying compositioncan be used directly by dispersion in water at a water temperature ofless than 45° C., better still less than 35° C., and even better stillat ambient temperature.

Another object of the present invention is to provide an emulsifyingcomposition for broad-spectrum cosmetic use, meaning that it isversatilein terms of the final products envisioned: from this standpoint, thecomposition according to the invention may be used in products asdiverse as lotions, creams, gels, milks, etc. Moreover, said compositionis advantageously nonirritant and nonallergic for the skin. It offersthe advantage, furthermore, of not being dependent on pH or on thepresence of electrolytes: in other words, its emulsifying capacity isunaffected by the pH of the medium or by the presence of mono-, di- ortrivalent salts. This criterion is all the more important since, ingeneral, products for cosmetic use and notably for topical applicationare liable to be subjected or exposed to pH variations (by way ofexample, the pH of the skin is slightly acidic, and ranges between 4 and6). Having a product which does not have any particular limit for use interms of pH thus represents a very great technical advantage for acosmetic composition.

Lastly, another object of the present invention is to provide acomposition for cosmetic use that offers a broad range of sensorialproperties of interest, such as, in particular, a sensation of freshnesson the skin, or an unctuous texture. Specifically, the emulsifyingcomposition of the invention allows the easy production of O/W emulsionsthat are both stable and very fine and which have tailorable texturesand exhibit a fresh, silky and nongreasy feel, even where the contentsof disperse fatty phase are high. It is thus possible to obtainemulsions that have a good emollient effect on the skin and also a goodmoisturizing effect on the upper layers of the epidermis.

The entirety of these objectives, constituting a complex technicalproblem to be solved, is ultimately achieved by virtue of the principalsubject of the present invention, this being an emulsifying composition,especially for cosmetic use, which enables the production of anoil-in-water (O/W) emulsion, comprising:

-   1) at least one cyclodextrin,-   2) and at least one O/W emulsifier of natural origin,

the O/W emulsifier having a hydrophilic-lipophilic balance (HLB) greaterthan 8, preferentially greater than or equal to 9.

The calculation of the HLB takes account of the molecular masses of thehydrophilic portions and the molecular mass of the molecule in question,and can be obtained according to the following equation:

$HLB = 20\frac{Molecular\mspace{6mu} mass\mspace{6mu} of\mspace{6mu} hydrophilic\mspace{6mu} portion}{Molecular\mspace{6mu} mass\mspace{6mu} of\mspace{6mu} the\mspace{6mu} molecule}$

In the present application, the term “cyclodextrin” denotes and includesany cyclodextrins otherwise known, such as unsubstituted nativecyclodextrins containing from 6 to 12 glucose units bonded by covalentbonds between carbons 1 and 4, and especially alpha-, beta- andgamma-cyclodextrins containing respectively 6, 7 and 8 glucose units.

This term likewise covers “cyclodextrin derivatives”, these beingmolecules in which at least some of the hydroxyl groups OH have beenconverted into groups OR, where R denotes, generally, an alkyl group.From this standpoint, the cyclodextrin derivatives include, inparticular, methylated and ethylated cyclodextrins, but also thosesubstituted with a hydroxyalkyl group, such as hydroxypropylated andhydroxyethylated cyclodextrins.

The preferred cyclodextrins according to the present invention arealpha-, beta- and gamma-cyclodextrins, with native beta-cyclodextrinbeing most preferred.

The cyclodextrin may in particular take the form of a crystalline,pseudocrystalline or amorphous powder.

In the present application, the term “O/W emulsifier of natural origin”denotes any molecule obtained from renewable resources, especially oneextracted from or secreted by plants, microorganisms or algae andenabling, after physical, chemical or enzymatic modification, theproduction of a water-in-oil O/W emulsion, or of promoting the stabilityof such an emulsion. Also included under this definition are thereforeproducts called O/W co-emulsifiers of natural origin.

The applicant has been able to observe, after numerous tests andexperimental designs, that quite surprisingly and unexpectedly, thecombination, with a cyclodextrin, of an emulsifier of natural originhaving a hydrophilic-lipophilic balance (HLB) greater than 8,preferentially greater than or equal to 9, making it possible in amanner known per se to obtain an O/W emulsion, far from having negativeconsequences on the stability and the quality of O/W emulsions, on thecontrary has a very favorable effect. It is thus advantageously possibleto reduce the amount of emulsifier of natural origin required to obtaina satisfactory and stable emulsion, and, moreover, to finely adjust thetexture and the sensory profile of the emulsion.

Without wishing to be tied to any particular theory, it appears that thepresence of very small amounts of an O/W emulsifier of natural origingreatly facilitates the formation in situ of inclusion complexes betweenthe cyclodextrin and certain specific molecules present in the dispersefatty phase, and in the form of colloidal, solid or semiliquidparticles, which take up position at the oil and water interfaces. Theseparticles are very compatible physically and sensorially with the skinor the hair, and do not damage animal cell membranes.

It has been shown that the combination of cyclodextrin with smallamounts of an O/W emulsifier of natural origin having ahydrophilic-lipophilic balance (HLB) greater than 8, preferentiallygreater than or equal to 9, makes it possible to obtain very stableemulsions with drops less than 30 µm in size, or even less than 10 µm insize. It has also been shown that this addition allows the ultimateviscosity of the O/W emulsion to be adjusted. By virtue of thisadjustment of the viscosity, combined with the droplet size of less than30 µm, or even 10 µm, the texture of the emulsions can be advantageouslyadjusted.

The O/W emulsifier of natural origin, which has a hydrophilic-lipophilicbalance (HLB) of greater than 8, preferentially greater than or equal to9, is preferably present in the emulsifying composition in a ratio ofbetween 0.01 and 1 part, preferably between 0.05 and 0.5 part, morepreferentially between 0.10 and 0.35 part, and even better still between0.15 and 0.30 part per 1 part by weight of cyclodextrin.

This O/W emulsifier of natural origin may also be selected from productswhich are naturally biodegradable in hydrated natural medium, especiallywith a hydrophilic-lipophilic balance (HLB) of between 8 and 20,preferably between 9 and 16, even better still between 11 and 14.

As an example, this O/W emulsifier of natural origin may be selectedfrom the following products, provided they meet the above conditionrelating to the HLB: alkyl polyglucosides; mixtures of at least onealkyl poly glucoside and at least one fatty alcohol; nonethoxylatedfatty esters of polyols, and especially from nonethoxylated fatty estersof glycerol, polyglycerols, sorbitol, sorbitan, anhydrohexitols such as,more particularly, isosorbide, of mannitol, of xylitol, of erythritol,of maltitol, of sucrose, of glucose, of polydextrose, of hydrogenatedglucose syrups, of dextrins, and of hydrolyzed starches.

The O/W emulsifier of natural origin is preferably selected to benaturally biodegradable in a hydrated natural environment. It mayespecially comprise nonethoxylated fatty esters of polyols obtained fromfatty acid or by transesterification from an oil or mixtures of oils.The fatty acids used comprise from 8 to 22 carbon atoms, preferably from10 to 18 carbon atoms, and more particularly from 12 to 18 carbon atoms.These acids may be linear or branched, saturated or unsaturated, and maypossess one or more pendent hydroxyl functions. The oils may besaturated or unsaturated, from liquid to solid at ambient temperature,and may optionally possess hydroxyl functions, preferably with an iodineindex of between 1 and 145, and more particularly from 5 to 105.

The O/W emulsifier of natural origin may more particularly be selectedfrom polyglycerol esters and preferably from esters obtained from thereaction of polyglycerols comprising from 2 to 12 glycerol units,preferably from 3 to 10 glycerol units, with at least one unhydrogenatedor partially hydrogenated plant oil with an iodine index of between 1and 15, and more particularly from 5 to 10. They may in particular beoleic, stearic, palmitic, lauric, diisostearic and caprylic esters ofpolyglycerols and in particular the following products: Polyglyceryl-5Dioleate with an HLB of approximately 8 (such as Dermofeel® G 5 DO fromEvonik Dr. Straetmans GmbH), Polyglyceryl-2 Caprate with an HLB ofapproximately 9 (such as Hydriol® PGC.2 from Hydrior), Polyglyceryl-3Stearate with an HLB of approximately 9 (such as Dermofeel® PS fromEvonik Dr. Straetmans GmbH), Polyglyceryl-2 Laurate with an HLB ofapproximately 9 (such as Dermofeel® G2L from Evonik Dr. StraetmansGmbH), Polyglyceryl-3 Palmitate with an HLB of approximately10 (such asDermofeel® PP from Evonik Dr . Straetmans GmbH), Polyglyceryl-10Diisostearate with an HLB of approximately 11 (such as Dermofeel® G10 DIfrom Evonik Dr. Straetmans GmbH), Polyglyceryl-6 Caprylate with an HLBof approximately 11.5, Polyglyceryl-5 Laurate with an HLB ofapproximately13 (such as Dermofeel® G5L from Evonik Dr. StraetmansGmbH), Polyglyceryl-3 Caprate with an HLB of approximately 14 (such asHydriol® PGC.3 from Hydrior), Polyglyceryl-4 Caprate with an HLB ofapproximately 14 (such as Massocare PG4 C from Masso), Polyglyceryl-10Monolaurate with an HLB of approximately 14.8, Polyglyceryl-6 Caprylatewith an HLB of approximately 15 (such as Dermofeel® G 6 CY from Dr.Straetmans GmbH/Evonik), Polyglyceryl-10 Laurate with an HLB ofapproximately 16 (such as Dermofeel® G 10 L from Dr. StraetmansGmbH/Evonik).

The O/W emulsifier of natural origin is preferably selected from alkylpolyglucosides, sometimes also called alkyl polyglycosides, anddesignated by the acronym APGs. These emulsifiers are nonionicsurfactants that are well known per se. Patent FR 2 948 285 gives apresentation of them in terms of structure, and explains how to preparethem. They can be represented by the following general formula (I):R₁—O—(R₂—O)_(p)—(S)_(n) wherein:

-   S represents a reducing saccharide, which may comprise between 5 and    6 carbon atoms,-   R1 denotes a linear or branched alkyl and/or alkenyl radical    comprising approximately 8 to 24 carbon atoms, or an alkylphenyl    radical of which the linear or branched alkyl group comprises    approximately 8 to 24 carbon atoms,-   R2 denotes an alkylene radical comprising from 2 to 4 carbon atoms,-   n denotes a value ranging from 1 to 15,-   p denotes a value ranging from 0 to 10.

The term “reducing saccharide” denotes, in formula (I), the saccharidederivatives which do not exhibit in their structures a glycosidic bondestablished between an anomeric carbon and the oxygen of an acetal groupas defined in the reference manual: Biochemistry, Daniel Voet/Judith G.Voet, p. 250, John Wyley & Sons, 1990. The oligomeric structure (S)_(n)can be in any form of isomerism, whether it is optical isomerism,geometric isomerism or positional isomerism; it can also represent amixture of isomers.

According to one particular aspect of the present invention, in thedefinition of the compounds of formula (I), S represents a reducingsaccharide selected from glucose, dextrose, sucrose, fructose, idose,gulose, galactose, maltose, isomaltose, maltotriose, lactose,cellobiose, mannose, ribose, xylose, arabinose, lyxose, allose, altrose,dextran or tallose and more particularly a reducing saccharide selectedfrom glucose, xylose or arabinose.

A first preferred variant of alkyl polyglucosides according to thepresent invention are C₁₂—C₂₀ alkyl glucosides, that is to say thecompounds of formula (I) wherein:

-   R1 more particularly denotes a linear or branched alkyl and/or    alkenyl radical comprising approximately 12 to 20 carbon atoms,-   p takes a value ranging from 0 to 3, and preferentially equal to    zero,-   S denotes glucose, fructose or galactose, and more preferentially    glucose.

A second preferred variant of alkyl polyglucosides according to thepresent invention are the C₁₂—C₂₀ alkyl glucosides of the firstpreferred variant, wherein:

-   R1 more particularly denotes a linear alkyl radical comprising    approximately from 12 to 20 carbon atoms,-   p is equal to zero,-   S stands for glucose.

Alkyl polyglucosides of formula (I) are in particular commerciallyavailable under the names: Plantacare® 810 UP (R₁ is C₈-C₁₀/INCI:caprylyl/capryl glucoside), Plantacare® 818 UP (R₁ is C₈-C₁₆/ INCI:Coco-glucoside), Plantacare® 2000 UP (R₁ is C₈-C₁₆/INCI: decylglucoside) and Plantacare® 1200 UP (R₁ is C₁₂-C_(16/)INCI: laurylglucoside) sold by the company BASF; Macanol® 810 (R₁ is C₈-C₁₀),Macanol® 1200 (R₁ is C₁₂-C₁₄), Macanol® 816 (mixture of R₁ being C₈,C₁₀, C₁₂, C₁₄, C₁₆) sold by the company FCI Technology; Neocare MF 0718(R₁ is C₈-C₁₀/INCI: caprylyl/capryl glucoside), Neocare MF 0012 (R₁ isC₁₂-C_(14/)INCI: lauryl glucoside), Neocare MF 0002 (R₁ isC₈-C_(16/)INCI: decyl glucoside), Neocare MF 818 (R₁ is C₈-C_(16/)INCI:coco glucoside) sold by the company Neochem; Tego Care CG 90 (R₁ isC₁₄-C_(16/)INCI: cetearyl glucoside) sold by the company EvonikHealthcare.

The O/W emulsifier of natural origin can be a mixture consisting of atleast one alkyl polyglucoside and at least one fatty alcohol. In thesemixtures, the alkyl polyglucosides can be selected from all the alkylpolyglucosides of use in the invention, that have been described above.Linear or branched fatty alcohols having a total number of carbon atomsranging from 8 to 24 can be used as fatty alcohols of use for mixingwith the alkyl glucosides.

Mixtures of alkyl glucosides and fatty alcohols that are of use in theinvention and commercially available are those sold by the companySEPPIC: Montanov™ 14 (INCI: Myristyl Alcohol & Myristyl Glucoside),Montanov™ 202 (INCI: Arachidyl Alcohol and Behenyl Alcohol and ArachidylGlucoside), Montanov™ 68 (INCI: Cetearyl Alcohol & Cetearyl Glucoside),Montanov™ 82 (INCI: Cetearyl Alcohol and Coco-Glucoside), Montanov™ S(INCI: Coco-Glucoside & Coconut Alcohol), Montanov™ L (INCI: C₁₄-C₂₂Alcohols & C₁₂-C₂₀ Alkyl Glucoside).

The preferred mixture of alkyl polyglucoside and fatty alcohol is thatsold by SEPPIC under the name Montanov™ L, which is a mixture of C₁₄-C₂₂fatty alcohols and of C₁₂-C₂₀ alkyl polyglucosides (INCI: C₁₄-C₂₂Alcohols & C₁₂-C₂₀ Alkyl Glucoside). The more preferred mixture of alkylpolyglucoside and fatty alcohol is that sold by SEPPIC under the nameMontanov™ 68 (INCI: Cetearyl Alcohol & Cetearyl Glucoside).

The O/W emulsifier of natural origin can also be selected from fattyesters of dextrins or of hydrolyzed starches, in particular in the formof sodium octenylsuccinate esters. These may, for example, be productsmarketed by the applicant under the names Cleargum® and in particularthe products Cleargum® CO 01 and Cleargum® CO 03.

The emulsifying composition of the invention makes it possible to obtainadvantageous sensorial effects, such as a particular texture or asensation of freshness, according to the proportions used.

The advantageous properties of said emulsifying composition result fromthe combination of the two compounds used, which exhibit high synergy interms of emulsion stability and of sensorial properties. Despite thehighly satisfactory results obtained whatever the proportions in whichthese compounds are combined, the results obtained are particularlyconvincing when the compounds are combined in very specific ratio.

More particularly, each of the various constituents of the presentemulsifying composition according to the invention may be integratedinto a different phase prior to the emulsification. Alternatively, thevarious components of the present composition of the invention are mixedwith one another to form what will hereinafter be denoted an“emulsifying system”; it being possible for said emulsifying system tobe added to either of the two immiscible phases in order to allow theformation of an O/W emulsion. The invention, advantageously, allowsthese two embodiments with the same compounds, thereby providingincreased room for maneuver and greater simplicity of use.

Such an emulsifying composition of the invention has the advantage,especially, of being entirely of natural origin, and of being utilizableby a cold process, and more particularly at ambient temperature. Saidcomposition of the invention is for cosmetic use and, in that context,is not sensitive to reasonable variations in pH or in salinity of themedium, and is neither irritant nor liable to provoke allergies,especially skin allergies. Furthermore, the composition of the inventionmay be used for producing any type of emulsion, especially Pickeringemulsions, and is therefore suitable for a wide variety of usages:creams, milks, serums, lotions, etc.

The emulsifying composition of the invention enables the production ofPickering emulsions, which advantageously may be stabilized by organicparticles which are compatible with the skin or the hair. It maycomprise, as a complement, other products which are capable of formingor stabilizing Pickering emulsions, such as silicas and granularoctenylsuccinate starches in the form of calcium or aluminum salts.

The emulsifying composition preferably also comprises at least onepolyol.

The polyols addressed for the present application are all the polyolsotherwise known, and especially maltitol, mannitol, xylitol, erythritol,sorbitol, and glycerol, with glycerol and sorbitol being the preferredpolyols. Preferably this polyol is crystallized or else is present inthe form of a powder.

According to the present invention, the emulsifying composition, inparticular for cosmetic use and capable of making it possible to obtainan emulsion of oil-in-water (O/W) type, contains, in % by weight:

-   1) from 40% to 95% of at least one cyclodextrin,-   2) from 5% to 40% of at least one O/W emulsifier of natural origin,    preferably selected from alkyl polyglucosides, mixtures of at least    one alkyl polyglucoside and at least one fatty alcohol, and    nonethoxylated fatty esters of polyols, having a    hydrophilic-lipophilic balance (HLB) greater than 8, preferentially    greater than or equal to 9,-   3) and from 0% to 40% of at least one polyol.

This emulsifying composition of the present invention is preferablycharacterized in that it contains, in % by weight:

-   1) from 45% to 85% of at least one cyclodextrin,-   2) from 5% to 30% of at least one O/W emulsifier of natural origin,    preferably selected from alkyl polyglucosides, mixtures of at least    one alkyl polyglucoside and at least one fatty alcohol, and    nonethoxylated fatty esters of polyols, having a    hydrophilic-lipophilic balance (HLB) greater than 8, preferentially    greater than or equal to 9,-   3) and from 10% to 40% of at least one polyol.

This composition of the present invention is most preferablycharacterized in that it contains, in % by weight:

-   1) from 40% to 80% of at least one cyclodextrin,-   2) from 10% to 20% of at least one O/W emulsifier of natural origin,    preferably selected from alkyl polyglucosides, mixtures of at least    one alkyl polyglucoside and at least one fatty alcohol, and    nonethoxylated fatty esters of polyols, having a    hydrophilic-lipophilic balance (HLB) greater than 8, preferentially    greater than or equal to 9,-   3) and from 10% to 30% of at least one polyol.

Preferably, the O/W emulsifier of natural origin having ahydrophilic-lipophilic balance (HLB) greater than 8 is a product whichis naturally biodegradable in a hydrated natural medium, and mostpreferentially a mixture of at least one alkyl polyglucoside and atleast one fatty alcohol.

Another subject of the present invention relates to a Pickering O/Wemulsion composition, in particular for cosmetic use, characterized inthat it contains, per 1 part by weight of at least one cyclodextrin,between 0.01 and 1 part, preferably between 0.05 and 0.5 part, morepreferentially between 0.10 and 0.35 part, and even better still between0.15 and 0.30 part of at least one O/W emulsifier of natural origin, thelatter preferably being selected from alkyl polyglucosides, mixtures ofat least one alkyl polyglucoside and of at least one fatty alcohol, andnonethoxylated fatty esters of polyols, having a hydrophilic-lipophilicbalance (HLB) greater than 8, preferentially greater than or equal to 9.

The O/W Pickering emulsion composition of the invention may alsocomprise a fatty phase which may, at ambient temperature (25° C.) beliquid, such as, for example, plant oils, or else solid as in the caseof waxes. This liquid fatty phase may be mineral, animal, plant orsynthetic in origin and may be composed of hydrocarbon-based oils oreven possibly of silicone oils. A hydrocarbon-based oil is an oil formedessentially, or even consisting, of carbon and hydrogen atoms andoptionally of oxygen and nitrogen atoms, it being possible for this oilto contain alcohol, ester, ether, carboxylic acid, amine and/or amidegroups.

This composition preferably contains one or more oils which are liquidat ambient temperature (25° C.), preferably at least one nonvolatileliquid oil. A nonvolatile liquid oil refers to an oil capable ofremaining on the skin at ambient temperature and atmospheric pressurefor at least one hour.

The liquid fatty phase advantageously comprises one or more nonvolatileoils which impart an emollient effect on the skin. Mention may be madeof fatty esters such as cetearyl isononanoate, isotridecyl isononanoate,isostearyl isostearate, isopropyl isostearate, isopropyl myristate,isopropyl palmitate, butyl stearate, hexyl laurate, isononylisononanoate, 2-ethylhexyl palmitate, 2-hexyldecyl laurate, 2-octyldecylpalmitate, 2-octyldodecyl myristate or lactate, 2-diethylhexylsuccinate, diisostearyl malate, tracetin, tricprin, caprylic/capric acidtriglycerides, glycerol triisostearate, tocopherol acetate, higher fattyacids such as myristic acid, palmitic acid, stearic acid, behenic acid,oleic acid, linoleic acid, linolenic acid or isostearic acid, higherfatty alcohols such as oleyl alcohol, plant oils such as avocado oil,camelia oil, hazelnut oil, Tsubaki oil, cashew nut oil, argan oil,soybean oil, grapeseed oil, sesame oil, corn oil, wheatgerm oil, colzaoil, sunflower oil, cotton oil, jojoba oil, peanut oil, olive oil, andmixtures thereof, plant butters such as karite butter and cameliabutter.

These oils may be hydrocarbon oils or silicone oils, such as liquidparaffin, squalane oil, petroleum jelly, dimethylsiloxanes, and mixturesthereof.

The liquid fatty phase may also optionally comprise volatile oils. Avolatile oil is an oil which is capable of evaporating from the skin inless than one hour at ambient temperature and atmospheric pressure.Volatile oils may, for example, be selected from silicone oils ortriglycerides of short fatty acids, for reducing the greasy feel.

The O/W Pickering emulsion composition of the invention preferablycontains only oils of renewable origin, and especially oils or buttersof plant origin, preferably refined. These oils and butters are ideallyin tune with the emulsifier system which is a subject of the invention,in the sense that they allow very stable emulsions to be obtained, withhigh whiteness and a readily adjustable viscosity.

The emulsifying composition of the invention advantageously allows thepreparation of O/W emulsions having very high oil contents. This type ofO/W emulsion rich in oil is commonly difficult to obtain in a formstable over time with conventional emulsifiers. The oil content of thefinal O/W emulsion is preferably between 10 and 65% by weight, andpreferably of the order of 20 to 55% by weight. The plant oils or oilsof plant origin such as, for example, sunflower oil and isopropylpalmitate have the more particular effect of allowing the production ofstable emulsions, which do not give rise to creaming or to phaseseparation.

The composition of the invention may further comprise a rheologicalagent such as, especially, a thickening agent for the aqueous phase, agelling agent or a suspension agent, such as, for example, gums obtainedfrom plants, such as gum Arabic, konjac gum, guar gum or derivativesthereof; gums extracted from algae such as alginates or carrageenans;gums obtained from microbial fermentation such as xanthans, mannans,scleroglucans, or derivatives thereof; cellulose and its derivatives,such as carboxymethylcellulose or hydroxyethylcellulose; starch and itsderivatives such as, more particularly, modified starches, especiallyacetylated, carboxymethylated, octenylsuccinate or hydroxypropylatedstarches; and synthetic polymers such as polyacrylic acids or carbomers.

The composition of the invention preferably comprises a rheologicalagent selected from natural polysaccharides obtained from plants or fromfermentation, which are optionally modified. Xanthan and derivativesthereof make it possible more particularly to obtain O/W emulsionshaving very fine droplet sizes, even when used in a content of less than1% by weight of the total emulsion.

The emulsions obtained by using the emulsifying composition according tothe invention preferably have a droplet size of less than or equal to 30µm, preferentially less than or equal to 10 µm. The term “droplet sizeof the emulsion” is intended to mean the mean diameter of the dropletsof dispersed fatty phase in suspension in the aqueous phase. A lowdroplet size increases the stability of the emulsion by reducing therate of flocculation of the emulsion, and hence the rate of phaseseparation. The droplet size is dependent on a large number ofparameters and, in this respect, represents a feature which it isappropriate to monitor and which is not intrinsic to the formulation ofthe emulsifying system. The droplet size is measured using a LEICA DMLSoptical microscope at x10 magnification.

The composition of the invention may further comprise a preservativeselected from benzyl alcohol, dehydroacetic acid, and mixtures thereof.

The composition of the invention preferably has a Brookfield viscosityof greater than 3000 mPas at 25° C., preferably greater than 5000 mPasat 25° C. The viscosity is measured using a Brookfield DV-II+Proviscometer which is rotated at a speed of 20 revolutions per minute incontact with the product sample. The resistance of the product to thisrotary movement is recorded for a minute and converted intomPascal-second. For each sample, the viscosity is measured three timesand the arithmetic mean of the three values is retained. A spindlesuitable for the measured viscosity is selected according to thefollowing ranges: the spindle selected is the spindle SP3 when theviscosity is less than or equal to 5000 mPa.s, SP4 when the viscosity isbetween 5000 mPa.s and 7000 mPa.s and SP5 when the viscosity is greaterthan or equal to 7000 mPa.s.

To characterize the sensorial properties of the emulsifier systems ofthe invention, use is made of sensorial descriptors and a corresponding5-step sensorial evaluation protocol. These 5 steps correspond to thevarious phases of application of a care product: appearance, pickup,spreading after 1 minute, after 2 minutes. During these 5 phases, anumber of sensorial descriptors are evaluated by a panel of evaluators,who award a score which may range from 0 to 10.

The composition of the invention preferably exhibits a whitenessdescriptor of greater than 8. The whiteness descriptor is defined by thepalette of colors in FIG. 1 . The product is examined under a lamp andcompared with the color palette by a panel of evaluators.

The composition of the invention preferably exhibits a brightnessdescriptor of greater than or equal to 8. The brightness is defined bythe propensity of the product to reflect light.

The composition of the invention preferably exhibits a spreadingdescriptor of greater than 8. The spreading is evaluated by examiningthe product after the placement on the hand of 50 to 100 µl of theproduct, during its spreading in 10 rotations, under a lamp. The lessthe resistance to movement between the 5th and 10th turn on the hand,the greater the spreading.

The composition of the invention preferably exhibits a film-formingdescriptor of greater than 8. The film-forming descriptor corresponds tothe propensity of the product to form a continuous film when slid overthe skin 2 minutes after having performed 10 rotations.

A further subject of the present invention is a process for producing anO/W Pickering emulsion composition, especially for cosmetic use, whichcomprises the following steps:

-   a) the dispersion in an aqueous phase of an emulsifying composition    comprising at least one cyclodextrin and at least one O/W emulsifier    of natural origin, the latter being present in a ratio of between    0.01 and 1 part, preferably between 0.05 and 0.5 part, more    preferentially between 0.10 and 0.35 part, and even better still    between 0.15 and 0.30 part, per 1 part by weight of at least this    cyclodextrin; it being possible for this O/W emulsifier of natural    origin to be selected in particular from at least one alkyl    polyglucoside, at least one mixture of at least one alkyl    polyglucoside and at least one fatty alcohol, and at least one    nonethoxylated fatty ester of polyols, more preferentially selected    from mixtures of at least one alkyl polyglucoside and of at least    one fatty alcohol, having a hydrophilic-lipophilic balance (HLB) of    less than 8, preferentially greater than or equal to 9,-   b) the addition, to the mixture obtained in step a), of a fatty    phase, preferably in an amount of between 10 and 65% by weight, and    preferably of about 20 to 55% by weight, relative to the final    weight of the emulsion, with mechanical stirring sufficient to allow    the fatty phase to be dispersed as fine droplets in the aqueous    phase and for an O/W emulsion which has a droplet size of less than    or equal to 30 µm, preferentially less than or equal to 10 µm, to be    obtained.

According to one variant, the process of the invention for producing anO/W Pickering emulsion composition, especially for cosmetic use,comprises the following steps:

-   a) the dispersion in a fatty phase of an emulsifying composition    comprising at least one cyclodextrin and at least one O/W emulsifier    of natural origin, the latter being present in a ratio of between    0.01 and 1 part, preferably between 0.05 and 0.5 part, more    preferentially between 0.10 and 0.35 part, and even better still    between 0.15 and 0.30 part, per 1 part by weight of at least this    cyclodextrin; it being possible for this O/W emulsifier of natural    origin to be selected in particular from at least one alkyl    polyglucoside, a mixture of at least one alkyl polyglucoside and at    least one fatty alcohol, and a nonethoxylated fatty ester of    polyols, more preferentially selected from mixtures of at least one    alkyl polyglucoside and of at least one fatty alcohol, having a    hydrophilic-lipophilic balance (HLB) of greater than 8,    preferentially greater than or equal to 9; the fatty phase    preferentially representing between 10 and 65% by weight, and    preferably about 20 to 55% by weight, of the final weight of the    emulsion,-   b) and the addition of the mixture obtained in step a) to an aqueous    phase, with mechanical stirring sufficient to allow the fatty phase    to be dispersed as fine droplets in the aqueous phase and for an O/W    emulsion which has a droplet size of less than or equal to 30 µm,    preferentially less than or equal to 10 µm, to be obtained.

It will be possible to understand the invention more clearly by means ofthe nonlimiting exemplary embodiments described below.

EXAMPLE 1

It will be possible to understand the invention more clearly by means ofthe nonlimiting exemplary embodiments described below, and byexamination of the appended figures:

-   FIG. 1 represents the range of colors used for evaluating the    whiteness descriptor;-   FIG. 2 is a photograph of 6 O/W emulsions obtained from emulsifying    compositions of the invention.

Six compositions in O/W emulsion form are produced according to theinvention, using the following protocol. The compositions of these 6compositions are reported in table 1.

To start with, a gelling agent is dispersed in water, with stirringusing a deflocculating blade at 1000 revolutions per minute. Thetemperature of the water is set at 40° C. when the gelling agent isxanthan gum, and at 70° C. when the gelling agent ishydroxyethylcellulose.

Beta-cyclodextrin is then wetted in glycerol, and thebeta-cyclodextrin/glycerol mixture is added to the water/gelling agentmixture with stirring at 1000 revolutions per minute, to give an aqueousphase.

The amount of beta cyclodextrins is set at 2% or at 5% by mass of thecomposition, depending on the cases.

Separately, the alkyl polyglucoside Montanov 68 (INCI: cetearyl alcohol& cetearyl glucose), from the company SEPPIC, is added to sunflower oilor to isopropyl palmitate with magnetic stirring, at 40° C., to obtainan oily phase.

The oily phase is then emulsified in the aqueous phase at 40° C. withstirring at 1500 revolutions per minute, for 15 minutes.

A preservative is added (mixture based on benzyl alcohol anddehydroacetic acid).

Table 1 % Beta-cyclodextrin Oil (30%) Emulsifier (1%) Thickener (0.7%) 15 Sunflower Montanov™ 68 Hydroxyethylcellulose 2 5 Sunflower Montanov™68 Hydroxyethylcellulose 3 2 Isopropyl Palmitate (IPP) Montanov™ 68Hydroxyethylcellulose 4 2 Sunflower Montanov™ 68 Xanthan 5 2 IsopropylPalmitate (IPP) Montanov™ 68 Xanthan 6 5 Isopropyl Palmitate (IPP)Montanov™ 68 Xanthan

FIG. 2 is a photograph of the 6 O/W emulsions obtained, according to theformulations given in table 1.

It is noted that all the emulsions according to the invention comprising1% of Montanov™ 68 (cetearyl alcohol and cetearyl glucose) and 2 or 5%of beta-cyclodextrin make it possible to obtain stable O/W emulsions,using only 1 wt% of customary O/W emulsifier.

For each of these compositions, measurements are made of the viscosity,droplet size, whiteness, spreading, greasy character, and penetrativecharacter. The compositions will be designated indiscriminately usingthe terms samples or product in the remainder of the present detaileddescription.

The viscosity is measured using a Brookfield DV—II+Pro viscometer. Aspindle of fixed size (spindles SP2 to SP7, used according to theviscosity levels in accordance with the instrument setpoints) is rotatedat a speed of 20 revolutions per minute in contact with the productsample. The resistance of the product to this rotational movement isrecorded for one minute and converted into mPascal-second, denotedmPa.s. For each sample, the viscosity is measured three times and thearithmetic mean of the three values is retained.

The whiteness descriptor is defined by the palette of colors in FIG. 1 .The product is examined under a lamp and compared with the color paletteby a panel of evaluators.

The spreading is evaluated by examining the product after the placementon the hand of 50 to 100 µl of the product, during its spreading in 10rotations, under a lamp. The less the resistance to movement between the5^(th) and 10^(th) turn on the hand, the greater the spreading.

The greasy character of the compositions is evaluated by examinationunder a lamp of product, 1 minute after having performed 10 rotations ofthe product on the skin. A panel of evaluators then evaluates theresistance of the product when the skin to which it has been applied isplaced between the thumb and the index finger and a rubbing movement isapplied. The panel of evaluators also takes account of the oily ornonoily appearance imparted to the skin.

Lastly, the penetrative character of the product is evaluated byexamination under a lamp of the product two minutes after havingperformed 10 rotations of the product on the skin, by carrying outsliding over the skin. A panel of evaluators then evaluates the amountof product residue recovered.

The results obtained for the 6 O/W emulsion compositions are set out intable 2.

Table 2 Viscosity in mPa.s (spindle used) Droplet size (microns) WhiteSpreading Greasiness Penetration 1 12 120 (SP5) Less than 10 10 7 7 10 212 233 (SP5) Less than 10 10 7 7 10 3 4417 (SP3) Less than 10 10 8 5 104 4917 (SP3) From 10 to 30 9 10 7 8 5 3940 (SP3) From 10 to 20 10 10 610 6 4517 (SP3) From 10 to 30 9 10 9 7

The viscosity of the emulsions increases slightly when the concentrationof beta-cyclodextrin increases: it goes from 3900-4900 mPa.s with 2% ofbeta-cyclodextrin to more than 12 000 mPas with 5%. Similarly, theviscosity is higher when the thickener used is cellulose rather thanxanthan: it goes from 4500 to 12 000 mPa.s. The emulsifying compositionsof the invention enable the realization, advantageously, of a very wideviscosity range, allowing the preparation both of milks and of viscouscreams.

It may be noted that all of the O/W emulsions obtained using theemulsifying compositions of the invention exhibit excellent sensorialproperties (scores ranging from 6 to 10 according to the criteria ofwhiteness, spreading, greasiness, and penetration).

The emulsions are less white when the oil used is sunflower oil thanwhen the oil used is isopropyl palmitate (denoted IPP): the descriptoris 10 out of 10 in the case of the sunflower oil, compared to 9.33 outof 10 on average in the case of isopropyl palmitate. However, thewhiteness of isopropyl palmitate remains satisfactory.

The spreading is significantly easier with xanthan than with cellulose,and goes from 7.33 with cellulose to 10 with xanthan.

1. An emulsifying composition, in particular for cosmetic use, allowingan oil-in-water (O/W) emulsion to be obtained, the emulsion comprising:a. at least one cyclodextrin, and b. and at least one O/W emulsifier ofnatural origin, wherein the O/W emulsifier is selected from fatty eatersof dextrins or of hydrolyzed starches. in the form of sodiumocteoylsuccinate ester. the O/W emulsifier having ahydrophilic-lipophilic balance (HLB) greater than 8, preferentiallygreater than or equal to
 9. 2. The emulsifying composition as claimed inclaim 1, characterized in that the O/W emulsifier is present in theemulsifying composition in a ratio of between 0.01 and 1 part,preferably between 0.05 and 0.5 part, more preferentially between 0.10and 0.35 part, and even better still between 0.15 and 0.30 part, per 1part by weight of cyclodextrin.
 3. The emulsifying composition asclaimed in claim 1, wherein said at least one cyclodextrin is selectedfrom alpha-, beta-, and gamma-cyclodextrins, preferably from nativebeta-cyclodextrin.
 4. The emulsifying composition as claimed in claim 1,wherein the cyclodextrin is present in the form of a crystalline,pseudo-crystalline or amorphous powder.
 5. The emulsifying compositionas claimed in claim 1, wherein the O/W emulsifier is also selected fromproducts which are naturally biodegradable in a hydrated natural mediumwith a hydrophilic-lipophilic balance (HLB) of between 8 and 20,preferably between 9 and 16 and even better still between 11 and
 14. 6.(canceled)
 7. The emulsifying composition as claimed in claim 1 , alsocomprising at least one polyol, which is preferably selected frommaltitol, mannitol, xylitol, erythritol, sorbitol and glycerol.
 8. Theemulsifying composition as claimed in claim 1, wherein the compositioncontains, in % by weight: a. 40% to 95% of at least one cyclodextrin, b.5% to 40% of at least one O/W emulsifier of natural origin, wherin theO/W emulsifier is selected from fatty esters of dextrins or ofhydrolyzed starches in the form of sodium octenylauccinate esters,having a hydrophilic-lipophilic balance (HLB) greater than 8,preferentially greater than or equal to 9, and c. and 0% to 40% of atleast one polyol.
 9. A composition of the O/W Pickering emulsion type,in particular for cosmetic use, characterized in that it contains, per 1part by weight of at least one cyclodextrin, between 0.01 and 1 part,preferably between 0.15 and 0.30 part of at least one O/W emulsifier ofnatural origin, wherin the O/W emulsifer is selected from fatty estersof dextrins or of hydrolyzed starches, in the form of sodiumoctenylsuccinate esters having a hydrophilic-lipophilic balance (HLB)greater than 8, preferentially greater than or equal to
 9. 10. Thecomposition as claimed in claim 9, containing one or more oils which areliquid at ambient temperature (25° C.), preferably at least onenonvolatile liquid oil.
 11. The composition as claimed in claim 10,wherein the oil content of the final O/W emulsion is between 10 and 65%by weight, and preferably between 20 and 55% by weight.
 12. Thecomposition as claimed in claim 9, further comprising a rheologicalagent, preferably a thickener for the aqueous phase, a gelling agent ora suspension agent.
 13. The composition as claimed in claim 9, having adroplet size of less than or equal to 30 µm, preferentially less than orequal to 10 µm.
 14. (canceled)
 15. A process for producing a compositionof the O/W Pickering emulsion type, in particular for cosmetic use,comprising the following steps: a) the dispersion in an aqueous phase ofan emulsifying composition comprising at least one cyclodextrin and atleast one O/W emulsifier of natural origin, wherein the O/W emulsifieris selected from fatty esters of dextrins or of hydrolyzed starches inthe form of sodium octenylsuccinate esters the latter being present in aratio of between 0.01 and 1 part, preferably between 0.15 and 0.30 part,per 1 part by weight of at least this cyclodextrin; and having ahydrophilic-lipophilic balance (HLB) greater than 8, preferentiallygreater than or equal to 9, and b) the addition, to the mixture obtainedin step a), of a fatty phase, in an amount of between 10 and 65% byweight, with mechanical stirring sufficient to allow the fatty phase tobe dispersed as fine droplets in the aqueous phase and for an O/Wemulsion which has a droplet size of less than or equal to 30 µm,preferentially less than or equal to 10 µm, to be obtained.